1. Field of the Invention
This invention generally relates to a huller for the removal of the hull containing a pistachio nut. My invention finds particular application as a pistachio huller. In particular my invention is directed to a method and apparatus for a huller which ruptures and abrades the hull containing a pistachio nut.
2. Description of the Prior Art
The current methods and apparatuses in use for pistachio dehulling work adequately and are primarily wet process hullers using large volumes of water.
It is noted, in U.S. Pat. No. 4,304,665 by Jay J. McFarland and Bertram E. Saunder for a "Pistachio Huller" that the pistachio industry has grown commercially in the San Joaquin Valley of the State of California during recent years with substantial acreage of this delicious nut being planted. These plantings are now in production and without the cheap labor of foreign countries it is not economically feasible to hull the harvested pistachios by hand. Noted in that patent is the statement that insofar as they could determine, prior to their invention, there had never been a practical mechanical huller for pistachios. The McFarland, et al patent discloses a two stage huller, the first stage to rupture the pericarps and to remove a portion of the hull and a second stage to strip the remaining portion of the pericarp from the shells. This patent discusses one embodiment used in connection with water wherein a water nozzle provides water to moisten and soften the pericarp and to rinse the fragments of pericarp from the shell. This type of prior art huller, in application, is water assisted. As in other prior art hullers substantial amounts of water are used. As will be described in greater detail hereinbelow, my invention is a method and apparatus for the dry hulling of pistachio nuts and is directed to overcome the necessity for the use of water while hulling pistachio nuts and other associated problems of the prior art.
It was in the late 1960's and early 1970's that most of 31,000 acres of pistachios were planted in the San Joaquin Valley of the State of California, that 1977 saw the first crop of California's pistachios, and that with little knowledge the questions then asked were: Now that we have them what do we do with them? How do we process them? More importantly, how do we hull them? My invention described hereinbelow answers the latter questions.
Further, the hulling of pistachio nuts is known to present unusual problems. The hulls must be promptly removed after harvest or discoloration to the pistachio shell will occur within 24 hours and damage to the nut can result if the pistachio hull is not promptly removed after harvest. Most commercial pistachio shells are dyed pink or red to hide this discoloration. The hull of the pistachio is stronger than most nuts and has a greater adherence to the shell than most nuts and it is therefore more difficult to remove.